On Thu, 24 Mar 2016, Sergey Kubushyn wrote:
On Thu, 24 Mar 2016, Marek Vasut wrote:
On 03/24/2016 12:54 AM, Sergey Kubushyn wrote:
On Thu, 24 Mar 2016, Marek Vasut wrote:
On 03/24/2016 12:47 AM, Sergey Kubushyn wrote:
On Thu, 24 Mar 2016, Marek Vasut wrote:
On 03/24/2016 12:08 AM, Tom Rini wrote: > On Wed, Mar 23, 2016 at 04:02:07PM -0700, Sergey Kubushyn wrote: > > On Wed, 23 Mar 2016, Tom Rini wrote: > > > > > On Wed, Mar 23, 2016 at 06:08:45PM +0100, Albert ARIBAUD > > > wrote: > > > > Hello Tom, > > > > > > > > On Wed, 23 Mar 2016 09:22:38 -0400, Tom Rini > > > > trini@konsulko.com > > > > wrote: > > > > > On Wed, Mar 23, 2016 at 01:53:35PM +0100, Albert ARIBAUD > > > > > wrote: > > > > > > Hello Marek, > > > > > > > > > > > > On Sun, 20 Mar 2016 17:15:34 +0100, Marek Vasut > > > > > > marex@denx.de > > > > > > wrote: > > > > > > > This patch decouples U-Boot binary from the > > > > > > > toolchain on > > > > > > > systems where > > > > > > > private libgcc is available. Instead of pulling in > > > > > > > functions > > > > > > > provided > > > > > > > by the libgcc from the toolchain, U-Boot will use > > > > > > > it's own set > > > > > > > of libgcc > > > > > > > functions. These functions are usually imported from > > > > > > > Linux > > > > > > > kernel, which > > > > > > > also uses it's own libgcc functions instead of the > > > > > > > ones > > > > > > > provided by the > > > > > > > toolchain. > > > > > > > > > > > > > > This patch solves a rather common problem. The > > > > > > > toolchain can > > > > > > > usually > > > > > > > generate code for many variants of target > > > > > > > architecture and > > > > > > > often even > > > > > > > different endianness. The libgcc on the other hand > > > > > > > is usually > > > > > > > compiled > > > > > > > for one particular configuration and the functions > > > > > > > provided by > > > > > > > it may > > > > > > > or may not be suited for use in U-Boot. This can > > > > > > > manifest in > > > > > > > two ways, > > > > > > > either the U-Boot fails to compile altogether and > > > > > > > linker will > > > > > > > complain > > > > > > > or, in the much worse case, the resulting U-Boot > > > > > > > will build, > > > > > > > but will > > > > > > > misbehave in very subtle and hard to debug ways. > > > > > > > > > > > > I don't think using private libgcc by default is a > > > > > > good idea. > > > > > > > > > > > > U-Boot's private libgcc is not a feature of U-Boot, > > > > > > but a fix > > > > > > for some > > > > > > cases where a target cannot properly link with the > > > > > > libgcc > > > > > > provided by > > > > > > the (specific release of the) GCC toolchain in use. > > > > > > Using > > > > > > private libgcc > > > > > > to other cases than these does not fix or improve > > > > > > anything; those > > > > > > other cases were working and did not require any fix > > > > > > in this > > > > > > respect. > > > > > > > > > > This isn't true, exactly. If using clang for example > > > > > everyone > > > > > needs to > > > > > enable this code. We're also using -fno-builtin > > > > > -ffreestanding > > > > > which > > > > > should limit the amount of interference from the > > > > > toolchain. And > > > > > we get > > > > > that. > > > > > > > > You mean clang does not produce self-sustained binaries? > > > > > > clang does not provide "libgcc", so there's no -lgcc > > > providing > > > all of > > > the functions that are (today) in: > > > _ashldi3.S _ashrdi3.S _divsi3.S _lshrdi3.S _modsi3.S > > > _udivsi3.S > > > _umodsi3.S div0.S _uldivmod.S > > > which aside from __modsi3 and __umodsi3 are all __aeabi_xxx > > > > There is also _udivmoddi4 pulled from libgcc for 64-bit > > division > > since we > > switched to 64-bit all around ARM. It comes from clock > > calculations for > > video, e.g. from drivers/video/ipu_common.c for i.MX6. > > Well, this is an example of why we both don't want libgcc ever > nor > do we > want to overly expand what we do offer. In this case isn't it > an > example of something that should be using lldiv/do_div/etc?
I haven't seen the _udivmoddi4 emitted in my tests. Linux's libgcc copy also doesn't implement the function. Which toolchain do you use and which target did you compile?
I'm using my own armv7hl-linux-gnueabi toolchain built for hard float. Linux arm libgcc does have arch/arm/lib/div64.S file that provides __do_div64() function that is used by do_div() from include/asm/div64.h for 32-bit ARM platform. Sure, arm64 has neither div64.h nor div64.S. We _DO_ have div64.h (that is totally different from what Linux provides) but no div64.S in arch/arm/lib.
In that case, we should just import div64.S from Linux on arm32 and be done with it ? Since we now have all the necessary macros thanks to the first four patches in this series, that should be trivial.
What do you think? I can bake a patch real quick, so you can test it ?
Sure I'll test it, no problems. Just bake the patch :)
Done, give it a go please.
OK, it didn't work, _udivmoddi4.o is still being pulled from libgcc. I'm analyzing it right now, will come up with more later today.
OK, it requires a CONFIG_USE_PRIVATE_LIBGCC defined to use private libgcc, my bad -- thought it would be automatic. Having that defined makes build fail complaining about assembly syntax in div64.S:
=== Cut === arch/arm/lib/div64.S: Assembler messages: arch/arm/lib/div64.S:185: Error: bad instruction `arm( orr r2,r2,r1,lsl ip)' arch/arm/lib/div64.S:186: Error: bad instruction `thumb( lsl r1,r1,ip)' arch/arm/lib/div64.S:187: Error: bad instruction `thumb( orr r2,r2,r1)' scripts/Makefile.build:316: recipe for target 'arch/arm/lib/div64.o' failed make[1]: *** [arch/arm/lib/div64.o] Error 1 Makefile:1214: recipe for target 'arch/arm/lib' failed make: *** [arch/arm/lib] Error 2 === Cut ===
Probably something is missing in div64.h? The Linux one is totally different. Digging in right now...
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